Heat-coil.



No. 802,684 PATBNTED OCT. 24, 1905.

F. B. 000K.

HEAT COIL APPLIGA'IION FILED APR. 3; 1905.

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1 %M%M. 17M 6% M UNITED STATES PATENT OFFICE.

HEAT-COIL.

Specification of Letters Patent.

Patented Oct. 24, 1905.

Application filed April 8, 1905. Serial No. 254,596.

To all whom it may concern.-

Be it known that I, FRANK B. Cook, a citi- Zen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented new and useful Improvements in Heat-Coils, of which the following is a specification, reference being had to the accompanying drawings illustrating same.

My invention relates to thermal protectors for electrical circuits, my object being, first, to provide a protector in which the heat generated therein is concentrated and confined to the parts where it is to be utilized 'to operate the device, and, second, to provide a large shearing-surface for the heat-susceptible material to give greater strength to the soldered connection when cool. To accomplish these ends, first, I reduce the size of certain heatconducting elements leading from the heated parts and leave an air-space surrounding the said heated parts as much as possible; second, I provide an enlarged end portion of the heated core, which affords a large surface for the heat-susceptible material; and, third, I employ a compact heat-producing winding wound upon the heated core near the enlarged end portion thereof.

I will more particularly describe my invention by reference to the accompanying drawings, in which- Figure 1 is a side elevation of the heat-coil of the invention. Fig. 2 is an end elevation of Fig. 1. Fig. 3 is a cross-sectional view of the heat-coil, taken on lineAB of Fig. 1. Fig. 4c is a cross-sectional view of the heat-coil, taken the same as Fig. 3, showing portions thereof in a separated relation. Fig. 5 is a cross-sectional view of a modified form of the heat-coil, taken the same as Fig. 3; and Fig. 6 is a view showing the heat-coil in use as a protective device.

Like characters refer to like parts in the several figures.

The heat-producing winding 0 is wound upon the heat-conducting core .9 in a compact manner and close to the enlarged end portion 5 of The enlarged portion 8 is inserted into a hollow portion or cap 1* of end connection-terminal 0, where it is normally secured by a heat-susceptible material 1). The heatproducing winding being thus concentrated near the heat-susceptible material, the heat generated therein is therefore applied direct to the soldered connection, which it unsolders. This end of s is preferably concave, so as not to allow the heat-susceptible material 1) to unite same to r on the fiat end surface thereof, which surfaces-would not separate by shearing when the device operates. The other end of core a is provided with a flat disk which is securely held between the insulating-washers 7 and m, the latter preferably being a split washer. The end connection-terminal (Z is provided with a hollow cup-shaped portion a at the inner end thereof, which is formed around the insulating-washers lo and m and the interposed disk end of core .9, so as to firmly hold the same therein. The inner portion n of end portion (Z is connected to the outer portion of (Z by a small neck 7b, which greatly reduces the conduction of heat from the heated parts. The terminals of the winding 0 are preferably connected to the core 3 and the cup-shaped portion a, respectively. The end terminals 0 and (Z are provided with respective grooves e and f therein, adapted to engage respective connecting-springs a and t. The inner portions of the heat-coil are inclosed by an insulating-shell b, which may be split and sprung on in place.

Springs 2, and a are provided with tongues Z 14 respectively, which are adapted to firmly hold the end connection-terminals (Z and c of the heat-coil in contact therewith. Line conductors w and a: are connected to springs 2i and a, respectively. Spring o is preferably connected to earth through conductor y. \Vhen the heat-coil operates, as shown in Fig. 4, spring it engages spring 1;, and thus grounds conductor a. This operation of the heat-coil also breaks the circuit between conductors w and Fig. 5 shows a modified form of the heatcoil in which the end connection-terminals (Z and 0 are connected to the inner parts of the device by necks 7L2 and 0, respectively. In this form of the invention the heat is more nearly confined to the inner portions of the device, as the heat-conducting paths to each end thereof are very small.

When an abnormally large current traverses the winding 0 of the heat-coil, it generates heat therein, and thus heats the core 8. The core conducts the heat from the winding 0 to the fusible material 19, which secures the hollow portion to the surface s of core .9. hen this heat is suflicient, the fusible material 19 softens, and as the device is held in a state of stress by springs t and uthe end terminal 0 now separates from the cores, as shown in Fig. 4. The neck it being small, very little heat is conducted to the end terminal (Z,

where it would be wasted. The enlarged portion of core 8 is preferably large in diameter and short in length, so as to give a large external surface for s and at the same time provide a large clearance between the members s and 0 when they separate. If the enlarged portion 8 were long, it would require a greater range of motion for spring a relatively to spring 5 to produce the same clearance between the members 8 and c. The con cave end of core 8 serves to compel the heat to be conducted through the fusible material p and not through the end surface of core .9.

In Fig. 5 the end terminal 0 separates from the core 8 when the fusible material p softens in a manner similar to that described for end terminal 0 and core 8. In this form of the in vention little heat is conducted to either of the end terminals (Z or 0 due to their respective small heat-eonducting connecting portions b and c".

The principal features of this invention are the compact winding wound close to the fusible material, the enlarged shearing-surface for the fusible material, and the reduced portions through which the end connecting-terminals are1 connected to the inner parts of the heatco1 Having thus described my invention, what I claim as new, and desire to secure by. Letters Patent, is

In a thermal protector for electric circuits, a core provided with enlarged cylindrical ends, a heat-producing Winding wound upon the said core between the said enlarged ends, a cupshaped portion in which one said enlarged end is normally secured by heat-susceptible material so that the two soldered parts may entirely separate when the heat-susceptiblematerial is softened, a second cup-shaped portion in which the other said enlarged end is insulatively secured, suitable terminals for the protector, small neck-like portions connecting the said cup-shaped portions to the respective terminals, a suitable shell inclosing the device from one terminal to the other, and an airspace between each cup-shaped portion and its terminal, inclosed by and within the said shell.

As inventor of the foregoing I hereunto subscribe my name, in the presence of two subscribing witnesses, this 4th day of April, A. l).

FRANK B. COOK.

\Vitnesses:

FREDERICK R. PARKER, F. W. PARDEE. 

